Radio tuning device



A. A. THOMAS RADIO TUNING DEVICE Filed Aug. 8, 1929 lNvENToR Patented Apr. 21, 1936 UNITED STATES PATENT OFFICE RADIO TUNING DEVICE Application August 8, 1929, Serial No. 384,289

10 Claims.

My invention relates to radio receivers, and its object is to provide simple means for holding the loudspeaker inoperative during rotation of the tuning shaft until the desired station is in tune. When the operator releases the hand knob (or other finger piece used for tuning), the loudspeaker is automatically cut into circuit. The normal hand pressure applied to the knob in turning it either way is suiTicient to operate a switch for putting the loudspeaker out of action. This control of the loudspeaker circuit is entirely automatic, requiring no thought on the part of the operator. My new tuner is also capable of operating with the loudspeaker in circuit by simply pulling on the knob when turning it. This loud tuning enables a person to try each station for a suitable program.

In a preferred embodiment of my invention, a rotary spindle carrying a inger piece passes through a rotary sleeve connected to the tuning shaft. A lost-motion connection between the sleeve and spindle permits a short spiral movement of the latter in either direction to open a Switch in the loudspeaker circuit while the sleeve remains stationary. Continued rotation of the spindle connects the sleeve and therefore the tuning shaft for operation. When a person lets go of the nger piece, suitable spring means automatically moves the spindle to normal circuitclosing position. The lost-motion connection between the sleeve and spindle may comprise a pin in the sleeve engaging a properly shaped cam slot in the spindle.

The novel features and practical advantages of my tuning device will be understood from a description of the accompanying drawing, in which Fig. l represents a vertical cross-section through a portion of a radio receiver provided with my invention, the hand-operated spindle being shown in normal position;

Fig. 2 is a View similar to Fig. 1, with the spindle in operated position to open a switch in the loudspeaker circuit;

Fig. 3 is an enlarged plan View of the front end of the sleeve through which the spindle passes;

Figs. 4 and 5 are enlarged cross-sections on lines 4 4 and 5 5 of Fig. l; and

Fig. 6 is an enlarged cross-section on line 6 6 of Fig. 2.

A bracket indicated as a whole by I is provided with bearings I2, I3 and I4. This bracket may be a single casting of aluminum, and is conveniently mounted on the bottom or base plate I of the radio cabinet by screws I5, or otherwise. The front end of tuning shaft I1 is mounted in bearing I4 and carries (or otherwise actuates) an indicator disk or dial I8 which is visible through an opening I9 in the front panel 20. The tuning elements on shaft I1 are represented convention- (Cl. Z50-20) ally by condenser elements 2 I, but any other kind of tuning elements may be used. A gear wheel 22 iixed on shaft I1 meshes with a pinion 23 mounted on a rotary sleeve 24, which is journalled in the aligned bearings I2 and I3 of bracket IU. A set-screw 25 or other suitable means holds the pinion '23 rigidly on sleeve 24. Axial movement of sleeve 24 is prevented by the ends of pinion 23 touching (or almost; touching) the adjacent ends of bearings I2 and I3.

A rotary spindle 26 mounted in bearing I2 and front panel 25 extends through sleeve 24 for in- .dependent movement. A knob or other nger .piece 21 attached toi the outer end of spindle 25 affords convenient means for operating the same. A pin 23 fixed in sleeve 24 extends into a V-shaped cam groove 29 in spindle 26, The cam groove 29 runs only part way around the spindle and terminates in end shoulders 35, which act as stops for pin 28. An expanding coil spring 3l around sleeve 24 is connected at its rear end 32 to the sleeve, and at its front end 33 to spindle 26. A simple way to connect the spring to the spindle without interfering with the rotary movements of the latter is to curve the end 33 of the spring and place it in a circular groove 34 of the spindle, The front end of sleeve 24 has a notch or slot 35 which permits contraction of the spring during the inward movement of spindle 25.

An insulating block 56 mounted on base plate I5 carries a pair of switch arms 31 and 38, which are supposed to be connected in the loudspeaker circuit, or in any other circuit controlling the operation of the loudspeaker. These switch arms may consist of spring blades which normally remain in pressure contact with each other to ho-ld the circuit closed. The spindle 26 terminates in an insulating projection 39, which may be a rounded piece of bakelite screwed into the spindle, or otherwise attached thereto. The two springs 3l and 31 normally hold the apex or central point of the V-shaped groove 29 against the pin 28 in sleeve 24, as clearly shown in Fig. 1. In other words, the spindle 25 is normally pushed outwardly or forwardly, so` that the switch arm 31 is in closed position. When a person grasps the knob 21 and turns it either way, the stationary pin 23 cams the spindle 25 rearward into the position shown in Fig. 2, whereby the switch arm 31 is automatically moved into open position to break the loudspeaker circuit. When either end 50 of cam groove 29 strikes the pin 28, the sleeve 24 is coupled to spindle 26, so that continued rotation of the latter rotates the sleeve and the tuning shaft I1. When the desired station is in tune, the operator lets go of knob 21, whereupon the tensioned springs 3| and 31 automatically push the spindle 26 forwardly to normal circuit-closing position,

They springs 3l and 31 are so light that they permit rearward movement of spindle 26 without undue pressure being applied to knob 21, so that even a child can operate the device. The spiral rotation of spindle 26 is so slight that a person is not aware of it when turning knob 21. In actual practice the inward movement of spindle 26 need not be more than one-eighth of an inch to open switch arm 31 with a wide gap. The coil spring 3| is really not necessary, because the spring blade 31 may be so tensioned as to push the spindle 26 back to normal position when the tuning knob 21 is released.

Sometimes a person operates the tuning knob of a radio set to find a station that broadcasts a suitable program. In that case it is necessary to have the loudspeaker going all the time, so that each broadcast program may be heard as it crosses the tuning point on the dial. This loud tuning is readily effected by simply pulling on knob 21 while it is being turned. This pulling action holds the pin 28 in the apex of cam groove 29, so that the spindle remains -in normal circuit-closing position during the tuning operation. During the operation of spindle 26 for silent tuning, the normal friction between sleeve 24 and tuning shaft I1 holds the sleeve stationary until the pin 28 encounters either end 30 of cam groove 29.

Although I have shown and described a specific construction, I Want it understood that my invention is not limited to the details set forth. Changes and modifications may occur to those skilled in the art without departing from the scope of the invention as defined in the appended claims.

I claim as my invention:

1. A radio receiver having a tuning shaft, a pair of rotary members, a rotary finger piece for actuating one of said members, mea-ns for connecting the other member to the tuning shaft, a lost-motion connection between said members to permit a preliminary movement of said first member without actuating the second member, and a switch controlled by the preliminary movements of said first member.

2. A radio receiver having a tuning shaft, a hand-operable spindle mounted for rotary movement, a rotary member connected to the tuning shaft of the receiver, means for connecting said spindle to said member for operating the latter after the spindle has been turned through a certain angle in either direction, said means including a lost-motion connection for obtaining an idle movement of said spindle through a predetermined arc, and a switch controlled by the idle movements of said spindle.

3. A radio receiver having a tuning shaft, a rotary sleeve connected to the tuning shaft, a rotary spindle extending through said sleeve, a finger piece for operating said spindle, a lostmotion connection between said sleeve and spindle for rotating the latter a certain amount without actuating said sleeve, and a switch controlled by the idle movements of said spindle.

4. A radio receiver having a tuning shaft, a rotary sleeve connected to the tuning shaft, a hand-operable spindle extending through said sleeve for rotary and slidable movement, a lostmotion connection between said sleeve and spindle to permit a preliminary spiral movement of the latter in either direction without actuating the sleeve, and a switch controlled by the preliminary movements of the spindle.

5. A radio receiver having a tuning shaft, a hand-operable spindle mounted for rotary and axial movement, a rotary member connected to the tuning shaft of the receiver, a lost-motion connection between said spindle and said member for turning the spindle through a certain angle without operating said member, a switch controlled by the axial movements of said spindle, and spring means for automatically restoring said spindle to normal position.

6. A radio receiver having a tuning shaft, a rotary sleeve connected to the tuning shaft, a hand-operable spindle extending through said sleeve for rotary and slidable movement, a lostmotion connection between said sleeve and spindle to permit a preliminary spiral movement of the latter in either direction without actuating the sleeve, said connection including a pin on the sleeve arranged to enter a cam groove on the spindle, said groove compelling axial movements of the spindle, a switch controlled by the axial movements of said spindle, and spring means for normally holding said pin and groove in predetermined relation.

7. A radio receiver having a tuning shaft, a

rotary sleeve connected to the tuning shaft, a hand-operable spindle extending through said sleeve for rotary and slidable movement, a lostmotion connection between said sleeve and spindle to permit a preliminary spiral movement of ment of the spindle in either direction through a certain angle, a switch controlled by the spiral movements of said spindle, and spring means for normally holding said pin in the apex of said groove.

8. A radio receiver having a tuning shaft, a hand knob rotatable in opposite directions, operative connections between said shaft and knob, means whereby the preliminary rotation of said knob through a certain angle automatically moves said knob axially without operating said shaft, and a loudspeaker switch controlled by the axial movement of said knob to effect silent tuning of said shaft.

9. A radio receiver having a tuning shaft, a spindle mounted for rotary and slidable movements, a finger piece for rotating said spindle in either direction, means whereby the preliminary rotary movement of said spindle is automatically accompanied by an axial movement thereof without operating said tuning shaft, connections whereby the continued rotation of the spindle after said preliminary rotary movement operates said tuning shaft, and a switch controlled by the axial movements of said spindle.

l0. A radio receiver having a tuning shaft, a rotary spindle connected to said shaft for operatgin the same, means for so mounting said spindle that the inner end thereof is free, said mounting means permitting axial movement of said spindle, a spring finger arranged to press against the inner end of said spindle for normally actuating the same axially in one direction, a knob on said spindle for rotating it and also moving it axially against the force of said spring finger, and electric contact means controlled by the movements of said spring finger.

ADOLPI-I A. THOMAS. 

